[geary] Bump required meson version to 0.50

[Michael Gratton <mjog src gnome org>]

commit 50d2a08663cabe8840d1a68ed992a61bcbe790a1
Author: Michael Gratton <mike vee net>
Date:   Fri Sep 27 17:26:37 2019 +1000

    Bump required meson version to 0.50
    
    Silences some warnings.

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index e0410dc9..6ba1df58 100644
--- a/meson.build
+++ b/meson.build
@@ -1,7 +1,7 @@
 project('geary', [ 'vala', 'c' ],
   version: '3.35.0',
   license: 'LGPL2.1+',
-  meson_version: '>= 0.49',
+  meson_version: '>= 0.50',
 )
 
 gnome = import('gnome')